Please help I really need it

I would've loved to help but someone already answered so I am also so they can be brainliest overall which in my opinion they helped out and it was nice stumbling uppon a friends question XD Nice seeing you again!!

1. is A??

2. is C??

3. is D??

4. is A??

I am making an educated guess saying as we cannot see the story. I have tried and hope this educated you and is 100% correct if not I sincerely apologize for making a great friend fail. ;w;

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation: